@jinjor 想像で話すと、fileタスクが近いんじゃないかと思いました。依存を調べるのではなく、依存を明示する感じです。

Prior to version 0.8.0, rake was only able to handle command line arguments of the form NAME=VALUE that were passed into Rake via the ENV hash. Many folks had asked for some kind of simple command line arguments, perhaps using “–” to separate regular task names from argument values on the command line. The problem is that there was no easy way to associate positional arguments on the command line with different tasks. Suppose both tasks :a and :b expect a command line argument: does the first value go with :a? What if :b is run first? Should it then get the first command line argument.